Mr. Murakami's novels are filled with entertaining psychopaths. But often there is a narrator, a stand-in for the author, who explains how their grotesque behavior is a logical response to a society that discourages expressions of individuality, self-reflection and personal ambition. "Popular Hits of the Showa Era" lacks any such guide, so the message is conveyed through extended metaphors (Mr. Murakami compares the characters to kamikaze pilots and Vietcong soldiers) and asides to the reader.